The invention relates to jam recovery and, more particularly, to a technique for eliminating malfunctions during a jam recovery purge cycle.
In using reproduction machines, there are various types of system shut downs or malfunctions that can occur in the various system operating modes. Operator involvement in correcting for the malfunction can often be extensive particularly in machines with various accessories such as sorters, collators, finishers and document handlers. The problem of correcting the malfunction, maintaining the integrity of the run in process, and minimizing down time and operator involvement can be significant.
Jam recovery and associated job recovery in many present copiers often requires the removal of documents and copy sheets stopped in several places in the machine even if the jam occurred in only one location to only one document. Jam recovery also often requires the manual restacking of the manually reordered document set back in the document handler tray, as well as the removal and throwing away of some or all of copies in process in the machine. This can be a time consuming and inefficient operation.
It is known for machines to provide a "cluster jam" of copy sheets by continuing to run sheet feeders after a jam so as to move unjammed sheets downstream of a jam point to an output tray, and to move other sheets to other suitable jam clearance cites, rather than leaving all the sheets in the path at their original positions when a jam occurs. Art of particular interest thereto is Xerox Corporation U.S. Pat. No. 4,231,567.
It is also disclosed in Xerox U.S. Pat. No. 5,045,881, for the operator to direct printed copy sheets to various different copy sheet output compiling stations, such as a stacking tray or a finisher compiler. Those copy sheets desired to be purged rather than provided as finished copies are directed to a particular designated station for operator removal and disposal. Preferably this designated purge station is a readily operator accessible tray.
In addition, Xerox U.S. Pat. No. 4,786,041, discloses an improved jam clearance and job recovery system for a recirculating document handler (RDH) for determining whether a jammed document is present in a first, second, or third document path jam zone, each jam zone corresponding to three distributed drive zones. The system automatically provides a preliminary job recovery operation before the RDH is fully stopped, by correspondingly operating the document feeding zones to feed unjammed documents in the third jam zone to a stacking tray, or to feed unjammed documents in the first jam zone to the platen, so that documents are directed to be operator removed from only one zone.
One difficulty not considered in these prior art devices is the potential for malfunctions and jams during a purge cycle or during the time that in process copy sheets are being manipulated for eventual disposal or use in the recovery procedure. This problem becomes more pronounced as the complexity, volume, and speed of operation increases in modern day machines. It is also not unusual in these modern day machines for copies in process to bunch up or deviate from normal process relationships due to inertia upon cycling down of the machine in response to machine malfunctions. The incorrect spacing of copy sheets in process often leads to further jams or malfunctions as the machine attempts to recover from the initial malfunction.
It would be desirable, therefore, to compensate for the deviant or irregular spacing relationships of copy sheets in process in response to machine recovery techniques after a machine jam or malfunction.
It is an object, therefore, of the present invention to be able to avoid further machine malfunctions during the recovery and cycle up period of a machine after a jam. Another object of the present invention is to maintain a suitable document spacing between copy sheets in process during a machine recovery operation. Another object of the present invention is to selectively engage independent copy sheet drives during job recovery to systematically purge unwanted copy sheets. Other advantages of the present invention will become apparent as the following description proceeds, and the features characterizing the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.